Method and system for wireless communication baseband processing

ABSTRACT

A method and system for prioritized baseband processing in a wireless communication network is disclosed. Parameters affecting processing times for performing tasks associated with different user equipments are evaluated and the tasks are prioritized based on the evaluation. Each task is performed by the baseband processor at a time that is based on the priority assigned to the task.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/217,824, filed Aug. 25, 2011, entitled “METHOD AND SYSTEM FORWIRELESS COMMUNICATION BASEBAND PROCESSING”, the entirety of which isincorporated herein by reference.

FIELD

The present invention relates to wireless communications, and inparticular to baseband processing of tasks in a wireless communicationsystem.

BACKGROUND

In current implementations of Long Term Evolution (LTE) wirelesscommunication networks, multiple user equipments (UEs), such as mobiledevices, compete for access to multiple radio channels maintained by abase station such as an evolved Node-B (eNB) base station. A schedulerof the base station schedules tasks to be performed by a basebandprocessor of the base station to service the multiple channels. Thesetasks must be performed within specific time frames defined byapplicable standards. These time frames are necessarily short to enablerapid adaptation to changing channel conditions.

The baseband processor of a base station is bounded in its ability toperform the various tasks that are scheduled due to limitations onprocessor computational speed and also due to complexity of requiredtasks. The limitations of the baseband processor give rise to occasionswhere time expires before the completion of one or more tasks that havebeen scheduled. When time expires before the completion of a task, theresult is a lost opportunity to perform the task, which in turn mayresult in loss of capacity and unfair distribution of service to usersof the UEs.

In response to limitations on processor performance, solutions have beenproposed that involve increasing processor computational power. This isa costly solution. Other solutions involve software architectures thatimprove processor efficiency, but gains in processor efficiency fromsoftware architectures still may not be satisfactory.

Therefore, there is a need for improving processing performance in abaseband processor of a base station for wireless communications.

SUMMARY

The present invention advantageously provides a method and system forscheduling tasks at a baseband processor in a wireless communicationsystem. According to one aspect, a method includes assigning a priorityto a task associated with a user equipment. The priority is based on atleast one parameter affecting a time available for processing the task.Tasks are processed in an order based on their assigned priorities.

According to another aspect, the invention provides a baseband processorthat includes a prioritizer and a scheduler. The prioritizer assigns apriority to a task. The priority is based on a comparison of parametersassociated with different sets of user equipment. Each parameter affectsa time of completion of a task associated with a user equipment. Thescheduler schedules tasks for execution based on their assignedpriorities.

According to another aspect, the invention provides a method ofperforming baseband processing in a baseband processor of a wirelesscommunication network. The method includes receiving a first parameteraffecting a first processing time of a first process to service a firstuser equipment in communication with the baseband processor via a firstradio transceiver coupled to the baseband processor. The method furtherincludes receiving a second parameter affecting a second processing timeof a second process to service a second user equipment in communicationwith the baseband processor via a second radio transceiver coupled tothe baseband processor. The first parameter is compared to the secondparameter and performance of the first and second processes arescheduled base on the comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of an exemplary embodiment of a wirelesscommunication system constructed in accordance with the principles ofthe invention;

FIG. 2 is a block diagram of an exemplary embodiment of a basebandprocessor that schedules tasks to be executed;

FIG. 3 is a flowchart of an exemplary process for assigning priority ofa task based on parameters that affect a processing time associated withthe task; and

FIG. 4 is a flowchart of an exemplary process for determining a priorityof a task based on a weighted average of at least two parameters.

DETAILED DESCRIPTION

Before describing in detail exemplary embodiments that are in accordancewith the present invention, it is noted that the embodiments resideprimarily in combinations of apparatus components and processing stepsrelated to baseband processing of tasks in a wireless communicationsystem. Accordingly, the system and method components have beenrepresented where appropriate by conventional symbols in the drawings,showing only those specific details that are pertinent to understandingthe embodiments of the present invention so as not to obscure thedisclosure with details that will be readily apparent to those ofordinary skill in the art having the benefit of the description herein.

As used herein, relational terms, such as “first” and “second,” “top”and “bottom,” and the like, may be used solely to distinguish one entityor element from another entity or element without necessarily requiringor implying any physical or logical relationship or order between suchentities or elements.

Referring now to the drawing figures, in which like referencedesignators denote like elements, there is shown in FIG. 1 a blockdiagram of an exemplary embodiment of a wireless communication systemconstructed in accordance with the principles of the invention, anddenoted generally as “10.” The wireless communication system 10 includesa base station 11. Base station 11 includes a baseband processor 12, anda plurality of Radio Frequency (RF) front ends, 14 a and 14 b, referredto collectively herein as RF front ends 14. The system 10 also includesuser equipment 16 a and 16 b, referred to collectively herein as userequipment 16. The number of RF front ends 14 and user equipment 16 shownin FIG. 1 is by way of example only. Greater or fewer RF front ends anduser equipment devices may be implemented. Also, in some embodimentsincluding the embodiment shown in FIG. 1, the RF front ends 14 arehoused with the baseband processor 12. The invention is not limited tosuch. It is contemplated that, in other embodiments, the RF front ends14 are housed separately and at a distance from the baseband processor12. Among other functions, the baseband processor 12 performs signalencoding and decoding and modulation and demodulation.

The baseband processor 12 also includes a prioritizer 18 and a scheduler20. The prioritizer 18 evaluates one or more parameters that affect atime of performing a particular task by the baseband processor. Forexample, a first parameter may be a distance between the basebandprocessor and a first RF front end in communication with a first userequipment and a second parameter may be a distance between the basebandprocessor and a second RF front end in communication with a second userequipment. A higher priority may be assigned to a process associatedwith the user equipment in communication with the RF front end that isfurther away from the baseband processor. A higher priority allows forlonger processing time to compensate for the time to propagate thelonger distance between the RF front end and the baseband processor.

The scheduler 20 schedules a task to be performed by the basebandprocessor based on the evaluation by the prioritizer 18. For example,the prioritizer 18 may determine which of two RF front ends is furtherfrom the baseband processor 12. In response, the scheduler 20 mayschedule a task associated with the RF front end further from thebaseband processor 12 before scheduling a task associated with the RFfront end that is closer to the baseband processor 12.

FIG. 2 is a block diagram of an exemplary embodiment of a basebandprocessor 12 that schedules tasks to be executed. The baseband processor12 includes memory 22 and a processor 24. The memory 22 may be Read OnlyMemory (ROM) and/or Random Access Memory (RAM). The memory 22 storesparameters that affect a time to process a task 26 and a queue ofpriority assignments 28. The processor 24 may include program counters,instruction and data caches, an instruction decoder unit, instructionbuffers, a dispatch unit, arithmetic logic units, floating pointexecution units, integer register files and floating point registerfiles. The processor 24 executes computer code that may be stored in thememory 22 to perform functions that include parameter prioritization 18and scheduling 20.

Prioritizer 18 may include determining a value of a parameter thataffects a time of performing a task. The prioritizer 18 may evaluate asingle parameter or a weighted average of a plurality of parameters. Asingle parameter or more than one parameter may be associated with aparticular task. The parameter evaluation of the prioritizer 18 isperformed for each of a plurality of tasks that may be performedsequentially or simultaneously. Such tasks may include routine basebandprocessing tasks such as encoding and modulation.

Prioritizer 18 prioritizes tasks based upon the evaluation of one ormore parameters affecting a time of processing a task. For example,prioritizer 18 may determine that one task should have a higher prioritythan another task, based on various parameters. For example, theprioritizer 18 may determine a status of a hybrid automatic repeatrequest (HARQ) process. In a HARQ process, the base station sends anencoded message to a user equipment. The user equipment evaluates theencoded message to determine if the message was received correctly. Theuser equipment then sends a HARQ message to the base station indicatingwhether the encoded message was received correctly. If the encodedmessage was not received correctly, the base station may send a secondencoded message. This process may be repeated several times if theencoded message is not properly received. When a first HARQ message istransmitted, the probability of error in receiving and decoding themessage is greatest. Conversely, on a third retransmission of the HARQmessage, the probability of receiving and decoding the message correctlyis greater.

The baseband processor detects whether the HARQ message has beenreceived within a bounded time and indicates an error. According to theLTE standard, one configuration specifies a 4 millisecond (ms) windowduring which a preset list of protocol stack activities must becompleted by the baseband processor 12. As a function of the HARQretransmission number, the largest loss of throughput occurs for latedetection of the first transmission success. Consequently, there isgreater urgency to process the response to a HARQ message with a lowerHARQ retransmission status. Therefore, when a status of the HARQ processis that more than one HARQ message has been sent to a user equipment 16in a single ongoing HARQ process, a lower priority is assigned by theprioritizer 18 to the task associated with the user equipment 16 towhich the HARQ messages are sent. Conversely, if the HARQ status is thatonly a first HARQ message has been sent, a higher priority is assignedby the prioritizer 18 to the task associated with the user equipment 16to which the HARQ message is sent.

As another example, the prioritizer 18 may determine a status of acoordinated multipoint (CoMP) access process associated with a userequipment 16 when the user equipment 16 is in a cell served by thebaseband processor 12 or when the user equipment 16 is in a cell otherthan the cell served by the baseband processor 12. A CoMP access processis a process that utilizes transmission and/or reception at multiplebase stations 11 in communication with a user equipment 16. For example,on the downlink, transmissions to the user equipment 16 from multiplebase stations 11 may be coordinated to appear as a single transmitterwith multiple antennas that are geographically separated. On the uplink,reception from a user equipment 16 may be at multiple base stations thatare coordinated to reduce interference and maximize signal to noiseratio.

Thus, at least one parameter evaluated by the prioritizer 18 may be astatus of a CoMP access process associated with the user equipment 16when the user equipment 16 is in a cell served by the baseband processor12. When the user equipment 16 is in a cell served by the basebandprocessor 12, a higher number of reception points in the CoMP accessprocess results in a lower priority being assigned to a task uponreception of CoMP information from all neighboring cells participatingin the CoMP process. A lower priority is assigned to increase thepotential that solicited uplink CoMP inputs are received at the basebandprocessor 12, before processing of the CoMP signals is scheduled.

Alternatively, at least one parameter evaluated by prioritizer 18 may bea status of CoMP access process associated with the user equipment whenthe user equipment 16 is in a cell that is different from a cellserviced by the baseband processor 12. When the user equipment 16 is ina cell that is different from the cell serviced by the basebandprocessor 12, a higher number of reception points in the CoMP processresults in a higher priority being assigned to the task.

The prioritizer 18 may include a comparator 30 to compare parametersassociated with different user equipments, and may prioritize tasksbased on the comparison. For example, the comparator 30 may compare afirst distance between the baseband processor and a first RF front end,and a second distance between the baseband processor and a second RFfront end, to determine which distance is greater. As another example,the comparator 30 may compare a first HARQ status (which may be a numberof retransmission attempts) of a HARQ process between a radio and afirst user equipment and a second HARQ status of a HARQ process betweenthe radio and a second user equipment, to determine which HARQ processhas the least number of retransmissions. As another example, thecomparator 30 may compare a first CoMP status of a first user equipment16 a to a second CoMP status of a second user equipment 16 b, todetermine which CoMP status has the highest number of reception points.

The scheduler 20 schedules tasks to be performed by the basebandprocessor 12 based on the priorities assigned to the tasks by theprioritizer 18. For example, the scheduler may schedule a start time forprocessing a task with a high priority before scheduling a later starttime for processing a task with a low priority. The scheduler 20 maywrite to a memory to form the queue of priority assignments 28.

Thus, one embodiment is a baseband processor 12 in a wirelesscommunication system 10. The baseband processor 12 includes aprioritizer 18 to assign a priority to a task based one or moreparameters affecting a time of processing various task to be schedule,and a scheduler 20 schedules a task for execution based on the assignedpriority. The prioritizer 18 may include a comparator 30 to compare afirst parameter affecting a time for completing a first process to asecond parameter affecting a time for completing a second process. Theprioritizer 18 may determine which of the first and second processes isassigned a higher priority based on the compared times for completion.The baseband processor 12 includes a memory 22 that stores evaluatedparameters 26 and stores a queue of prioritized tasks 28 to becompleted.

FIG. 3 is a flowchart of an exemplary process for assigning priority ofa task based on parameters that affect a processing time associated withthe task. Parameters that affect a processing time associated with atask include, but are not limited to, a distance between the basebandprocessor 12 and an RF front end 14, a status of a HARQ process, anumber of participants in a CoMP process, a Multiple Input-MultipleOutput (MIMO) state of a user equipment, a type of interferenceprocessing performed by the user equipment, and a number of iterationsof a decoder process executed by the baseband processor. Referring toFIG. 3, a parameter affecting a processing time associated with a taskis determined and evaluated (step S100). A priority is assigned to thetask based on the evaluation of the parameter (step S102). Prioritizedtasks are processed according to their assigned priorities (step S104),where execution of a higher priority task is started before startingexecution of lower priority tasks.

Thus, one embodiment is a method of performing baseband processing in abaseband processor 12 of a radio in a wireless communication network 10.The method includes receiving a first parameter affecting a firstprocessing time of a first process to service a first user equipment 16a in communication with the baseband processor via a first radiotransceiver 14 a coupled to the baseband processor 12. The methodfurther includes receiving a second parameter affecting a secondprocessing time of a second process to service a second user equipment16 b in communication with the baseband processor 12 via a second radiotransceiver 14 b coupled to the baseband processor 12. The firstparameter and the second parameter are compared, and performance of thefirst and second processes is scheduled based on the comparison.

FIG. 4 is a flowchart of an exemplary process for determining a priorityof a task based on a weighted average of at least two parameters. Abaseband processor determines a distance between the baseband processorand a radio transmitting to a user equipment 16 (step S106). In analternative embodiment, the distance between the baseband processor 12and the various RF front ends are predetermined and stored at thebaseband processor 12. As noted above, the larger the distance, thehigher the priority associated with the task. The baseband processorfurther determines a status of a HARQ process involving the userequipment (step S108). A higher HARQ retransmission status results in alower priority associated with the task.

The baseband processor also determines a status of a CoMP process (stepS110). When the user equipment for which the task is performed is in thecell being served by the baseband processor, a higher number ofreception points in the CoMP process results in a lower priority. Whenthe user equipment for which the task is performed is in a cell that isdifferent from the cell being serviced by the baseband processor, ahigher number of reception points in the CoMP process results in ahigher priority for the task.

In some embodiments, the baseband processor may also determine a MIMOparameter associated with the user equipment, more multiple inputs andoutputs resulting in higher priority (step S112). The baseband processormay also determine an interference parameter indicating a type ofinterference processing performed by the user equipment, (step S114), amore complex interference process resulting in the assignment of ahigher priority. The baseband processor may also determine a decodingparameter indicating a number of decoder iterations performed by thebaseband processor (step S116), where the higher the number of decoderiterations, the higher the priority. Other parameters that may beevaluated that affect a processing time associated with a task may beevaluated, including a signal to noise plus interference ratio, a blockerror rate, and a receiver type of the user equipment. Note that theinvention is not limited to the particular order shown in stepsS106-S116, and the invention does not require that each and every listedparameter be determined. The steps may be performed in any order, andnot every step need be performed. Further, other parameters may bedetermined in lieu of or in addition to the parameters shown in FIG. 4.

The baseband processor 12 may compute a weighted average of at least twoof the various parameters determined in steps S106-S116, (step S118).For example, the baseband processor 12 may compute:

Urgency=k1*(Distance)−k2*(CoMP status)−k3*(HARQ status),

where k1, k2, and k3 are determined empirically to minimize lostpayload. For instance, k1 and k2 may be based on known averageelectrical delays. A priority of a task may be assigned based on theweighted average, (step S120). For example, considering only the factorsof distance and CoMP status, the following table of urgencies may beconstructed:

Near Far CoMP Less Urgent More Urgent non-CoMP More Urgent Most UrgentWhen a CoMP process is in effect and the RF front end is near to thebaseband processor, the task to be performed may be deemed less urgent.When the CoMP process is in effect and the RF front end is far from thebaseband processor, the task to be performed may be deemed more urgent.If a CoMP process is not in effect and the RF front end is near thebaseband processor the task to be performed may be deemed more urgent,whereas, if the CoMP process is not in effect and the RF front end isfar from the baseband processor, the task to be performed may be deemedmost urgent.

Thus, one embodiment is a method of scheduling tasks for a basebandprocessor in a wireless communication system. The method includesevaluating at least one parameter that affects a processing time toperform a task associated with a user equipment. A priority of the taskis assigned based on the evaluation, and the task is processed based onthe priority. Multiple parameters may be evaluated and a weightedaverage of the parameters may be computed. The priority assigned may bebased on the weighted average. The weights of the weighted average maybe derived empirically to reduce lost capacity. Tasks are scheduledaccording to their assigned priority so that a task with a higherpriority is scheduled for execution before a task with a lower priorityis scheduled for execution.

The present invention can be realized in hardware, or a combination ofhardware and software. Any kind of computing system, or other apparatusadapted for carrying out the methods described herein, is suited toperform the functions described herein. A typical combination ofhardware and software could be a specialized computer system, e.g., arouter, having one or more processing elements and a computer programstored on a storage medium that, when loaded and executed, controls thecomputer system such that it carries out the methods described herein.The present invention can also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which, when loaded in a computingsystem is able to carry out these methods. Storage medium refers to anyvolatile or non-volatile storage device.

Computer program or application in the present context means anyexpression, in any language, code or notation, of a set of instructionsintended to cause a system having an information processing capabilityto perform a particular function either directly or after either or bothof the following a) conversion to another language, code or notation; b)reproduction in a different material form.

In addition, unless mention was made above to the contrary, it should benoted that all of the accompanying drawings are not to scale. It will beappreciated by persons skilled in the art that the present invention isnot limited to what has been particularly shown and described hereinabove. In addition, unless mention was made above to the contrary, itshould be noted that all of the accompanying drawings are not to scale.A variety of modifications and variations are possible in light of theabove teachings without departing from the scope and spirit of theinvention, which is limited only by the following claims.

What is claimed is:
 1. A method of scheduling tasks for a basebandprocessor in a wireless communication system, the method comprising:assigning a priority to a task associated with a user equipment based onat least one parameter affecting a length of time available forprocessing the task; processing the task based on the priority assignedto the task; and the at least one parameter being one of: a distancebetween the baseband processor and a radio transmitting to the userequipment; a status of a hybrid automatic repeat request (HARQ) process;and a status of a coordinated multipoint (CoMP) access processassociated with the user equipment when the user equipment is in a cellserved by the baseband processor.
 2. The method of claim 1, wherein, ifthe at least one parameter is the distance between the basebandprocessor and the radio, a longer distance results in a higher prioritybeing assigned to the task.
 3. The method of claim 1, wherein, if the atleast one parameter is the status of the HARQ process, a lower priorityis assigned to a task when the status is that more than one HARQ messagehas been sent to the particular user equipment in a single ongoing HARQprocess.
 4. The method of claim 1, wherein, if the at least oneparameter is the status of the CoMP access process associated with theuser equipment when the user equipment is in a cell served by thebaseband processor, a higher number of reception points in the CoMPaccess process results in a lower priority being assigned to the task inthe cell served by the baseband processor upon reception of CoMPinformation from all neighboring cells participating in the CoMPprocess.
 5. The method of claim 1, wherein the at least one parameter isa status of a CoMP access process associated with the user equipmentwhen the user equipment is in a cell that is different from a cellserviced by the baseband processor.
 6. The method of claim 5, wherein ahigher number of reception points in the CoMP access process results ina higher priority being assigned to the task.
 7. The method of claim 1,wherein the priority assigned to a task is based on a weighted sum ofparameters affecting the processing time to service the user equipmentassociated with the task.
 8. A method of performing baseband processingin a baseband processor of a wireless communication network, the methodcomprising: receiving a first parameter affecting a first processingtime of a first process to service a first user equipment incommunication with the baseband processor via a first radio transceivercoupled to the baseband processor; receiving a second parameteraffecting a second processing time of a second process to service asecond user equipment in communication with the baseband processor via asecond radio transceiver coupled to the baseband processor; comparingthe first parameter to the second parameter; scheduling performance ofthe first and second processes based on the comparison; and one of: thefirst parameter being a distance between the baseband processor and aradio in communication with the first user equipment and the secondparameter is a distance between the baseband processor and a radio incommunication with the second user equipment; the first parameter beinga status of a hybrid automatic repeat request (HARQ) of the first userequipment and the second parameter is a status of a HARQ of the seconduser equipment; and the first parameter being a status of a coordinatedmultipoint (CoMP) access process associated with the first userequipment and the second parameter is a status of a CoMP access processassociated with the second user equipment.
 9. A baseband processor in awireless communication system, the baseband processor comprising: aprioritizer configured to assign a priority to a task based on acomparison of parameters associated with user equipments, a parameteraffecting a time to completion of a task associated with a userequipment; a scheduler configured to schedule a task for execution basedon the priority assigned to the task; and the at least one parameterbeing one of: a distance between the baseband processor and a radiotransmitting to the user equipment; a status of a hybrid automaticrepeat request (HARQ) process; and a status of a coordinated multipoint(CoMP) access process associated with the user equipment when the userequipment is in a cell served by the baseband processor.
 10. Thebaseband processor of claim 9, wherein the prioritizer further comprisesa comparator, the comparator being configured to: compare a firstparameter affecting a time duration for completing a first process to asecond parameter affecting a time duration for completing a secondprocess; and determine which of the first and second processes isassigned a higher priority based on the compared parameters.
 11. Thebaseband processor of claim 9, further comprising a memory configured tostore a set of the parameters for each of a plurality of processes, eachprocess associated with a corresponding user equipment.
 12. The basebandprocessor of claim 11, wherein a stored parameter affecting a timeduration for performing a task is indicative of one of: a multiple inputmultiple output (MIMO) state of the user equipment; a type ofinterference processing performed by the user equipment; and a number ofiterations of a decoder process executed by the baseband processor. 13.The baseband processor of claim 9, wherein the at least one parameter isa status of a CoMP access process associated with the user equipmentwhen the user equipment is in a cell that is different from a cellserviced by the baseband processor.
 14. A method of performing basebandprocessing in a baseband processor of a wireless communication network,the method comprising: receiving a first parameter affecting a firstprocessing time of a first process to service a first user equipment incommunication with the baseband processor via a first radio transceivercoupled to the baseband processor; receiving a second parameteraffecting a second processing time of a second process to service asecond user equipment in communication with the baseband processor via asecond radio transceiver coupled to the baseband processor; comparingthe first parameter to the second parameter; and scheduling performanceof the first and second processes based on the comparison.
 15. Themethod of claim 14, wherein the first parameter is a status of a hybridautomatic repeat request (HARQ) of the first user equipment, and thesecond parameter is a status of a HARQ of the second user equipment. 16.The method of claim 14, wherein the first parameter is a status of acoordinated multipoint (CoMP) access process associated with the firstuser equipment, and the second parameter is a status of a CoMP accessprocess associated with the second user equipment.